In the fabrication of integrated circuits and displays, semiconductor, dielectric, and electrically conducting materials are formed on a substrate, such as a silicon substrate or a glass substrate. The materials, in some examples, can be formed by chemical vapor deposition (CVD), atomic layer deposition (ALD), physical vapor deposition (PVD), ion implantation, plasma or thermal oxidation, and nitridation processes. Thereafter, the deposited materials can be etched to form features such as gates, vias, contact holes and interconnect lines. In a typical deposition or etch process, the substrate is exposed to a plasma in a substrate processing chamber to deposit or etch material on the substrate surface. Other typical processes that may be performed on a substrate may include thermal processing techniques that may include rapid thermal processing (RTP), flash lamp, or laser annealing processes.
Physical vapor deposition (PVD), or sputtering, is one of the most commonly used processes in fabrication of integrated circuits and devices. PVD is a plasma process performed in a vacuum chamber where a negatively biased target (typically, a magnetron target) is exposed to a plasma of an inert gas having relatively heavy atoms (e.g., argon (Ar)) or a gas mixture comprising such inert gas. Bombardment of the target by ions of the inert gas results in ejection of atoms of the target material. The ejected atoms accumulate as a deposited film on a substrate placed on a substrate pedestal which generally faces the target. During the processes discussed above, the substrate is typically held on a substrate support having a substrate receiving surface. The support can have an embedded electrode that serves as a plasma generating device during processing and/or it may also be charged to electrostatically hold the substrate. The support can also have a resistance heating element to heat the substrate during processing, and/or a water cooling system to cool the substrate or to cool the support. One issue that arises is that as device sizes decrease the tolerance to variation across the substrate has become very low such that the alignment and positioning of a substrate relative to the substrate support, shadow ring, or other chamber components can affect the uniformity of the process results achieved on the substrate. In some cases, one or more regions in a process chamber may be unable to uniformly generate a plasma (e.g., plasma-enhanced chemical vapor deposition (PECVD), PVD), uniformly deliver heat to the substrate (e.g., RTP, PECVD), and/or have regions of non-uniform gas flow due to the position orientation of the gas inlet or exhaust in the processing chamber, which commonly creates the need to rotate the substrate to average out the non-uniformities seen in different areas of the processing region of the processing chamber.